值未从JList传递到另一个JList

Question

Here's my code. Why the values are not going into the second JList? Also, the second Jlist is not visible. All imports are in place and not visible in the following code:

public class Gui extends JFrame {

    private JList l;
    private JList l2;
    private JButton b1;
    public String [] cd = {"Album a", "Album b", "Album c", "Album d","Album e", "Album f", "Album g", "Album h"}; 

    public Gui(){

    super("Mover");
    l = new JList (cd);
    l.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
    b1 = new JButton("Move");

    b1.addActionListener(
            new ActionListener(){
                public void actionPerformed(ActionEvent event){
                    l2.setListData(l.getSelectedValuesList());
                }
            }
);


    setLayout(new FlowLayout());
    add(new JScrollPane(l));
    add(b1);
    add(new JScrollPane(l2));

}
}

Answer 1

Your JList l2 is null, You need to initialise it to before you can use it like you do with l

Add

l2 = new JList (/*your list2 or empty*/);

just after your initialisation of the JList l

Edit As I now see was mentioned in the comments